Fossilized egg shell pieces are revealing lost information about the elephant bird

ARI SHAPIRO, HOST:

Ostriches are the biggest birds on the planet today. Males can tower 9 feet tall, half of that their neck, and weigh in at more than 300 pounds. But there was once an even bigger bird, the elephant bird, which roamed Madagascar before dying out roughly a thousand years ago.

GIFFORD MILLER: So these are really big birds. They're something like 9 feet tall, they weigh well over 1,000 pounds. And they lay an egg that's like a foot and a half in length.

AILSA CHANG, HOST:

They lay an egg a foot and a half in length. Gifford Miller is with the University of Colorado, Boulder. He says elephant birds, which are distant relatives of emus and ostriches, once had the ability to fly. But when they landed in Madagascar, they may have encountered no serious predators, so they lost their flight skills and instead ballooned in size.

MILLER: They must have very flexible DNA that allows them to grow big fairly quickly. And they're at a size where they could sort of defend themselves from any natural predator who might be out there.

SHAPIRO: Miller's colleague Alicia Grealy, a researcher with the Australian government, says elephant birds are somewhat mysterious because there's not much left of them to study.

ALICIA GREALY: The skeletal fossil record is pretty patchy. There's not a lot of complete bones.

SHAPIRO: So instead of bones, they looked to the birds' fossilized eggshells instead, which litter sand dunes and beaches in Madagascar today.

GREALY: They're literally just lying there on the ground, tons of them.

MILLER: And to think that this is something that's a few thousand years old and still that well-preserved - and the eggshells, they look like pottery. They're so strong. They're not at all fragile.

SHAPIRO: Another advantage, the scientists say, is the eggshells preserve DNA a bit better than bone. Their team collected 960 shell fragments from sites all over the island.

MILLER: It was pretty exciting. We had a Malagasy guide with us at all times that could help us get around and negotiate with local little tiny kingdoms to get permission to be on the land and then to wander around and find these.

CHANG: Back at the lab, they ran a genetic analysis of the shards, and they found preliminary evidence for a previously unknown lineage of the birds in northern Madagascar.

GREALY: So that was kind of surprising because no skeletons have ever been found there.

CHANG: The results appear in the journal Nature Communications.

SHAPIRO: As for what happened to the elephant birds, the scientists say no one knows exactly why they disappeared. But they did vanish sometime after the first humans arrived on Madagascar.

CHANG: Suggesting that some combination of hunting and habitat change might have made humans a predator that even elephant birds were unable to match. Transcript provided by NPR, Copyright NPR.